Collision sensing system for vehicles and associated method

A collision sensing system for a vehicle having a vehicle body with a front end;

• a seat-occupant restraining device in a passenger compartment of the vehicle and a collision load bearing portion at the front end of said body;
• said collision sensing system comprising damper means connecting said load bearing portion to said front end of the body, said damper means including a movable part coupled to said load bearing portion to be displaced thereby when the load bearing portion is displaced by impact force in a collision and a normally stationary part in which said movable part is movable, said damper means being operative to couple the stationary part with the movable part when the movable part travels at a velocity exceeding a predetermined value whereby the stationary part tends to be displaced with the movable part, resisting means of limited strength opposing displacement of the stationary part to hold the stationary part substantially at rest until the stationary part is subjected to a force exceeding a predetermined value, and switch means coupled to said stationary part of said damper means for energizing said seat-occupant restraining device in response to displacement of said stationary part.

A method of operating a seat-occupant restraining device in response to collision of a vehicle, said method comprising sensing impact of a vehicle during collision by displacing a collision load bearing member rearwardly in response to said impact, damping the rearward travel of said collision bearing member by a damping assembly in which a movable member connected to the collision load bearing member for displacement therewith travels in a stationary member which itself is displaceable with respect to the body by deformation of an impact energy absorbing member, the damping being a function of the change of velocity of the vehicle during the collision, deforming said impact absorbing member when the change of velocity of the vehicle and thereby the damping exceeds a predetermined value, displacing an actuator connected to said stationary member by the effect of the travel of the stationary member when said damping exceeds said predetermined value, and actuating a seat-occupant restraining device by displacement of the actuator.